Effects of Pd- and Ta-buffer layer on magnetic and interfacial perpendicular properties of sputtered Co 2 FeSi/MgO heterostructures

Abstract

A series of Co₂FeSi (CFS)/MgO heterostructures with Pd and Ta buffers are fabricated by sputtering method. Perpendicular magnetic anisotropy (PMA) with energy density of ∼1 × 10⁶erg/cm³ is demonstrated in the annealed heterostructures deposited onto two heavy metal buffers. Pronounced influence of buffer layers on the magnetic and interfacial PMA properties is observed. Thicker magnetic dead layer and lower saturation magnetization are found in annealed Ta-buffered CFS/MgO heterostructure in contrast to Pd-buffered one. Wide window of MgO thickness exhibiting PMA is witnessed in the Pd-buffered heterostructure, in line with the enhanced PMA. PMA is shown to be insensitive to buffer thickness and is identified to dominantly originate from the heterostructure interface. Our results provide some useful information for design and integration of next-generation perpendicular spintronic devices based on CFS/MgO heterostructures.